I sent in my 920 for service since it had a crack in the top right corner of the screen.

Today I heard it would take 3-4 weeks because they needed to send it further, so I decided I can't wait that long and want my phone back as soon as possible. The crack itself is not noticeable unless you wanna see it, but it's there you know, on a one month old device.

No I don't think it will get worse because the crack itself is INSIDE the glass, you can't even feel it with the finger nails. I think some stone was inside the front speaker grill and created pressure and finally made a crack in the screen.